kern/53214: user triggerable KASSERT in exec_runproc

[alnsn%NetBSD.org@localhost]

>Number:         53214
>Category:       kern
>Synopsis:       user triggerable KASSERT in exec_runproc
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Apr 25 19:45:00 +0000 2018
>Originator:     Alexander Nasonov
>Release:        NetBSD 8.99.14
>Organization:
	XMM SWAP LTD
>Environment:
	NetBSD neva 8.99.14 NetBSD 8.99.14 (GENERIC_KASLR) #0: Sat Apr 14 21:57:15 BST 2018  alnsn@neva:/home/alnsn/netbsd-current/clean/src/sys/arch/amd64/compile/obj/GENERIC_KASLR amd64
	Architecture: x86_64
	Machine: amd64
>Description:
	Running a script with a relative path in the sheebang can trigger
	KASSERT and panic the system.
>How-To-Repeat:
	cd /tmp
	cat <<EOF > x.sh
	> #!sh
	> echo hi
	> EOF
	chmod +x x.sh
	ln -s /bin/echo sh
	./x.sh

	panic: kernel diagnostic assertion "resolvedname[0] == '/'" failed: file "/home/alnsn/netbsd-current/clean/src/sys/kern/kern_exec.c", line 939

	Full panic screen: https://pic.twitter.com/O6XAsoz4Xi

>Fix:
	Not known.